Electric Coil Winding

ABSTRACT

Various embodiments may include an electric coil winding comprising: an electric conductor; a non-conductive element wound in parallel to the electric conductor throughout a number of turns forming a coil; and a first retaining element arranged in a first end region of the coil. The non-conductive element may be mechanically secured to the retaining element by means an elastic tensile element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Stage Application of InternationalApplication No. PCT/EP2017/058190 filed Apr. 6, 2017, which designatesthe United States of America, and claims priority to DE Application No.10 2016 206 573.4 filed Apr. 19, 2016, the contents of which are herebyincorporated by reference in their entirety.

TECHNICAL FIELD

The present disclosure relates to electrical machines. Variousembodiments may include an electric coil winding comprising an electricconductor, a non-conductive element and at least one first retainingelement, wherein the electric conductor and the non-conductive elementare wound in parallel with one another in a plurality of turns.

BACKGROUND

In many known coil windings, electric conductors are wound in analternating arrangement with non-conductive elements, in a sequence ofmutually superimposed windings. The non-conductive elements arrangedbetween the conductor windings thereby insulate the individual conductorwindings from one another. The electric conductors can comprisesuperconducting or normally conducting conductor elements. In the caseof the superconducting conductor elements, additionally to thesuperconducting material, one or a plurality of normally conductingconductor paths can also be provided.

In conventional wet-wound coil windings, an adhesive and/or impregnatingagent is applied to the individual windings in conjunction with thewinding process and is then cured subsequently to the actual windingprocess, such that a mechanically and dimensionally stable coil bobbinis constituted. Dry-wound coils, i.e. coils incorporating no suchadhesive or impregnating agent, can also be embedded, adhesive-bonded,or impregnated further to the winding process, in order to obtain adimensionally stable coil bobbin of this type. However, there are alsodry-wound coils in which the windings are not mutually connected, or areonly partially or only loosely mutually connected. In dry coil windingsof this type, there is a risk that, once the coil has been wound, theindividual winding layers of the electric conductor and thenon-conductive element can become displaced in relation to one another,after the manufacture of the coil. Specifically, as a result of theelectrical operation of a coil winding of this type, or as a result oftemperature variations associated with the cooling or heat-up thereof toa service temperature which differs from the manufacturing temperature,forces can be generated which displace the individual winding layers inrelation to one another.

In order to resolve the issue of the potential displacement of theelectric conductor and/or of the non-conductive element from thefully-wound coil winding, the non-conductive element in conventionalcoil windings is typically mechanically secured to the ends of the coilwinding. For example, the non-conductive element can be screwed to thetwo contact elements which are employed for the electrical contacting ofthe electric conductor. In many cases, these are copper blocks, whichare arranged in radially interior and/or exterior regions of the coilwinding and, at the two end regions of the conductor, are electricallyconnected to the latter. If both the conductor and the non-conductiveelement are mechanically attached to these contact elements, any mutualdisplacement of the former two elements can sometimes be prevented, butonly for such time as there is no action of additional forces, or anyexpansion or contraction of said elements.

It is specifically problematic, however, if adjacent conductor branchesrepel each other during operation, or if the conductor and thenon-conductive element, during operation and/or in response to atemperature variation, undergo a different change in length. In suchcases, in the event of the conventional attachment of the windingelements, a mutual displacement of the different elements can easilyoccur. The compact and mechanically stable composite structure of thecoil winding can be compromised as a result. In dry-wound flat coils,and flat coils which are not subsequently embedded or adhesive-bonded, aproblem then arises, in that the conductor and/or the non-conductiveelement, in the axial direction, i.e. perpendicularly to the windingplane of the coil, can shift out of the coil plane. Such coils will thennot be mechanically stable in service.

SUMMARY

The teachings of the present disclosure may be embodied in an electriccoil winding which overcomes the above-mentioned disadvantages.Specifically, a coil winding which, even in the absence ofadhesive-bonding or embedding in a fixing medium, is mechanically stablein service. In service, the composite structure of the winding shouldthus be maintained, with no shifting of the electric conductor and thenon-conductive element in relation to one another, and no loss of themechanical integrity thereof in the coil winding.

For example, some embodiments may include an electric coil winding (1)comprising an electric conductor (3), a non-conductive element (5) andat least one first retaining element (7 a). The electric conductor (3)and the non-conductive element (5) are wound in parallel with oneanother in a plurality of turns. The first retaining element (7 a) isarranged in a first end region (9 a) of the coil winding (1). Thenon-conductive element (5) is mechanically secured to the retainingelement (7 a) by means of at least one elastic tensile element (11).

In some embodiments, both the electric conductor (3) and thenon-conductive element (5) are constituted of a strip material, and thecoil winding (1) is configured as a flat coil with mutually superimposedlayers of the strip material elements.

In some embodiments, the electric conductor (3) comprises asuperconducting conductor material.

In some embodiments, the first end region (9 a) is arranged in an outerradial position.

In some embodiments, the retaining element (7 a) is configured as anelectric contact element, to which the electric conductor (3) isconnected in an electrically conductive manner.

In some embodiments, the non-conductive element (5) is configured as aspacer between individual and mutually superimposed turns of theelectric conductor (3).

In some embodiments, the non-conductive element (5) incorporates one ormore cavities (13), through which a coolant fluid (15) can flow.

In some embodiments, the non-conductive element (5) comprises acorrugated strip (17).

In some embodiments, the non-conductive element (5) is at leastpartially constituted of a plastic.

In some embodiments, the non-conductive element (5) is configured with agreater width than the electric conductor (3).

In some embodiments, the non-conductive element (5), in an interiorregion (19) relative to the width thereof, incorporates a recess (21),or a series of recesses (21), in which the electric conductor (3) iscarried.

In some embodiments, the non-conductive element (5) is constituted of aplurality of parts (17, 18).

In some embodiments, the elastic tensile element (11) can exert atensile force of at least 5 N on the non-conductive element (5).

In some embodiments, the electric conductor (3) comprises at least twoconductor branches (3 a, 3 b), and wherein at least two adjacentconductor branches (3 a, 3 b) in the winding are configured for mutuallyopposing directions of current flow (Ia, Ib).

As another example, some embodiments may include a fault current limiterhaving an electric coil winding (1) as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

The teachings herein are further described hereinafter by way of anumber of exemplary embodiments, with reference to the attacheddrawings, in which:

FIG. 1 shows a schematic view of a bifilar flat coil winding of a faultcurrent limiter incorporating teachings of the present disclosure;

FIG. 2 shows a non-conductive element of the coil winding, configured asa spacer with an electric conductor arranged therein, in a schematicoblique view, incorporating teachings of the present disclosure;

FIG. 3 shows the first end region 9 a from FIG. 1, in a schematic sideview for a configuration according to the prior art; and

FIG. 4 shows the first end region 9 a from FIG. 1, in a schematic sideview incorporating teachings of the present disclosure.

DETAILED DESCRIPTION

Various embodiments of the teachings herein include a coil windingcomprising at least one electric conductor, at least one non-conductiveelement, and at least one first retaining element. The electricconductor and the non-conductive element are wound in parallel with oneanother in a plurality of turns, wherein the first retaining element isarranged in a first end region of the coil winding, and wherein thenon-conductive element is mechanically secured to the retaining elementby means of at least one elastic tensile element.

The elastic tensile element can be, for example, a tension spring, butcan also be another elastic element, by means of which thenon-conductive element is secured to the retaining element, by theaction of a tensile force. For example, this can be a rubber band, or anelement of a similarly elastic material, such as rubber. By theconfiguration of the elastic attachment of the non-conductive element tothe retaining element, the non-conductive element can be maintainedunder tension, separately from the electric conductor. Specifically, thecoil winding is thus configured such that the electric conductor ismechanically dissociated from the tensile force exerted by the elastictensile element.

For example, the electric conductor can be rigidly mechanically attachedto the retaining element, or to any other element. By this arrangement,the non-conductive element is maintained under mechanical tension,separately from the electric conductor. During the operation of the coilwinding and/or in the event of the cooling or heat-up thereof to aservice temperature, the forces occurring can be cushioned, and anydifferential variations in length between the electric conductor and thenon-conductive element can be offset. Accordingly, notwithstanding theaction of a force, there is then no unwanted displacement of theelectric conductor and/or of the non-conductive element from the localwinding plane.

In some embodiments, even a dry coil remains mechanically stable, as thenon-conductive element which is retained by a tensile force also securesthe electric conductor which is guided parallel thereto within theindividual turns of the winding. In the end regions of the coil winding,there is likewise no shifting of the conductive and non-conductiveelements out of the winding plane, as any variations in length can becompensated by the elastic tensile element, and do not need to becompensated by any displacement out of the winding plane. This alsoapplies specifically to the outermost turns of the winding, i.e. forexample the radially innermost and the radially outermost windings of aflat coil. In the event of the rigid attachment of the electricconductor and the non-conductive element, shifting of the windingelements associated with variations in the length thereof or electricalrepulsion between the conductor windings can very easily occur in theseend regions.

In the electric coil winding, both the electric conductor and thenon-conductive element may comprise a strip material. The coil windingmay comprise a flat coil with mutually superimposed layers of the stripmaterial elements. In other words, the coil can comprise a fixed windingplane, within which all the turns are wound. The strip materialconductor and the strip material non-conductive element can then bewound within this winding plane, such that the main surfaces of thestrips are respectively arranged perpendicularly to the winding plane.The strip material elements of the successive turns can then lie flush,one on top of another.

In this connection, however, the above-mentioned strip material elementsare not to be understood as flat strips only, but can also be present asstrip material elements of different geometries: specifically, thenon-conductive element may comprise a three-dimensionally structuredstrip. However, a flat strip geometry is also possible, both for thenon-conductive element and for the electric conductor.

Regardless of their exact configuration, flat coils having a stripmaterial electric conductor and a strip material non-conductive elementgenerally have the advantage that these winding elements are arrangedradially one on top of another, such that the elements in successiveindividual turns are mutually mechanically secured, and the entire coilwinding is mechanically stable, even in the dry form. By the applicationof a tensile force to the non-conductive element, exceptionally goodmechanical stability may then be achieved.

In some embodiments, the electric conductor comprises a superconductingmaterial. Specifically, the conductor may comprise a superconductingstrip conductor, in which a superconducting layer is applied to anormally conducting or non-conductive substrate. The superconductingmaterial can be a high-temperature superconductor. High-temperaturesuperconductors (HTS) are superconducting materials with a criticaltemperature in excess of K and, in certain material classes, for examplecuprate superconductors, in excess of 77 K, wherein the servicetemperature can be achieved by cooling with cryogenic materials otherthan liquid helium. HTS materials are also particularly attractive, asthese materials, depending upon the service temperature selected, canshow both high upper critical magnetic fields and high critical currentdensities. In some embodiments, the high-temperature superconductor cancomprise, for example, magnesium diboride or a ceramic oxidesuperconductor, for example a compound of the REBa₂Cu₃O_(x) type (REBCOfor short), where RE stands for a rare earth element, or a mixture ofsuch elements.

In coil windings with superconducting conductors, the mechanicalstability of dry-wound coils is of particular importance as, in manycases, any embedding or adhesive bonding of the coil is not desirable,for example in the interests of achieving an open structure in which thesuperconducting conductor can maintain close contact with a liquidcoolant. Cooling of the superconductor to a temperature below itscritical temperature can thus be achieved more easily.

In some embodiments, the first end region may be arranged in an outerradial position. In an outer radial region of this type, specifically ofa flat coil, it is particularly important to prevent any lateralshifting of the winding elements associated with electrostatic forces orvariations in length, as the outermost turns are not mechanicallysupported by any further turns, and are thus particularly susceptible tolateral displacement. In some embodiments, however, the first end regioncan, in principle, also be arranged in an inner radial position. In someembodiments, both an inner radial end region and an outer radial endregion of a coil winding can be configured in the manner described. Inother words, the non-conductive element, both internally and externally,can be secured to a retaining element by means of an elastic tensileelement. In some embodiments, on both sides, this attachment can bemechanically dissociated from any attachment of the electric conductor.In the inner and outer radial position respectively, a separateretaining element can be provided, to which the non-conductive elementis mechanically secured in both end regions thereof. However, both endregions of the conductor, and thus both retaining elements, can also bearranged in the outer radial position, as is frequently the case, forexample, in current limiter coils.

In some embodiments, the retaining element may comprise an electriccontact element, to which the electric conductor is connected in anelectrically conductive manner. In other words, the electric conductorcan be connected to the same retaining element as the non-conductiveelement. The conductor can be rigidly mechanically connected to thisretaining element and is thus mechanically dissociated from theelastically-secured non-conductive element. In some embodiments, thefirst retaining element can be an outer radial electric contact element.Additionally, some embodiments include a second retaining element,comprising an inner radial or an outer radial contact element, and towhich the non-conductive element, in its second end region, is likewisesecured by means of an elastic tensile element. The at least one contactelement can be, for example, a copper contact piece.

In some embodiments, the non-conductive element comprises a spacerbetween individual and mutually superimposed turns of the electricconductor. Specifically, the clearance thus achieved between thesuperimposed turns can be greater than the thickness of the electricconductor. The spacer can specifically be a radial spacer betweenradially superimposed turns of a flat coil. In some embodiments, thereis a radial clearance of at least 1 mm between the individual turns.

In some embodiments, the non-conductive element includes one or morecavities through which a coolant fluid can flow. When used with asuperconducting conductor, cooling to a temperature below the criticaltemperature can then be achieved by means of the coolant. In someembodiments having superconducting coil windings, the individual turnsare spaced by means of an intervening spacer, in order to permit a flowof coolant through the gaps thus constituted.

In some embodiments, the non-conductive element can comprise acorrugated strip. In the present context, a corrugated strip is a stripmaterial element having a corrugated profile. This can involve eitherregular or irregular corrugations. These may comprise sinusoidalcorrugations, or only approximately corrugated arrangements ofpolylines. In general, the corrugated strip comprises a series, in thelongitudinal direction, of sequentially arranged corrugation peaks andcorrugation troughs. By means of a structure of this type, thenon-conductive element functions as a spacer between the adjacent turnsof the electric conductor.

In some embodiments, the non-conductive element comprises a corrugatedstrip and one or more further components. For example, thenon-conductive element may comprise a combination of at least one suchcorrugated strip with one or more flat strips. The individual componentscan either be loosely arranged, one on top of another, or can bepermanently mechanically secured, for example by the adhesive bonding orwelding of the individual components. In some embodiments, thenon-conductive element can comprise a plastic. Plastics are generallywell-suited to the purposes of electrical insulation and, at the sametime, are sufficiently deformable to permit the winding thereof in acoil winding in the form of thin strips. For the purposes of electricalinsulation between the adjacent turns of the electric conductor, forexample, flat strips of plastics including, for example, polyester,polyethylene terephthalate (PET), polyimide (PI) ofpolytetrafluoroethylene (PTFE), specifically Hostaphan, Kapton orTeflon, can be employed. Plastics are also particularly suitable for anon-conductive element which is to function as a spacer. For employmentin conjunction with superconducting electric conductors, the plastic maybe designed for use in a cryogenic temperature range below the criticaltemperature of the superconductor. Specifically, the plastic can besuitable for immersion in the coolant fluid which is employed forcooling, including, for example, liquid nitrogen, liquid hydrogen,liquid helium or liquid neon, without losing its mechanical integrity.

In some embodiments, the non-conductive element has a greater width thanthe electric conductor. The width of these elements is generally to beunderstood as the extension thereof in a spatial direction which isperpendicular to their longitudinal extension, specifically theirmaximum extension perpendicularly to said longitudinal extension.Particularly in the case of strip material winding elements, thenon-conductive element may be wider than the electric conductor so theelectric conductor can then be embedded between the surrounding turns ofthe non-conductive element such that, in an axial direction of the coilwinding, it is protected against external mechanical influences. In suchembodiments, the path for any potential electric arcing between one turnof the conductor and the next is significantly extended. In this manner,the risk of unwanted electric arcing between the turns of the coilwinding may be reduced.

In some embodiments, the non-conductive element having a relativelybroad width can, in an interior region relative to the width thereof,incorporate a recess, or a series of recesses, in which the electricconductor is carried. In such an embodiment, the conductor—specificallyin a flat coil geometry—is then not only radially embedded between theadjacent turns of the non-conductive element, but is also secured in theaxial direction of the coil winding between sections of thenon-conductive element. By an arrangement of this type, the mechanicalstability of the entire winding may be improved, as the electricconductor is secured in position by the non-conductive element, and anylateral shift in the axial direction may be prevented, provided that thenon-conductive element remains under tension. A tensile force of thistype is however ensured by means of the mechanical attachmentincorporating teachings of the present disclosure.

In general, the non-conductive element may comprise a plurality ofparts. In some embodiments, at least one corrugated non-conductive stripmay be combined with one or more flat non-conductive strips. In someembodiments, in which the non-conductive element is at least partiallyconstituted of a plastic, plastic-based subelements can be mutuallybonded in a sectional arrangement by thermal welding, in order toconstitute an overall three-dimensional structure. A spacer for theturns of the electric conductor can thus be constructed in aparticularly simple manner. In some embodiments, the elastic tensileelement may exert a tensile force of at least 5 N on the non-conductiveelement. This tensile force can specifically act on the non-conductiveelement along a longitudinal direction thereof. By the configuration ofa tensile force in this manner, a reliable re-tensioning of thenon-conductive element can be achieved, by means of which effectiveretention is delivered and any axial shifting of the individual turnscan thus be prevented. Where the tensile element comprises a tensionspring, this can show, for example, a spring constant of at least 5N/mm.

In some embodiments, the electric conductor can comprise at least twoconductor branches, wherein at least two adjacent conductor branches inthe winding are configured for mutually opposing directions of currentflow. In some embodiments, the coil winding serves in a current limiteron the grounds that, by the alternation of the directions of currentflow in this manner, the inductances of the two winding elements aremutually compensated. In the normal operating state of the currentlimiter, the alternating current losses can be kept low accordingly.

In an arrangement having only two conductor branches, the coil windingcan specifically be configured in the form of a “bifilar coil winding”.In arrangements having more than two conductor branches, directions ofcurrent flow can either be varied between each adjacent pair ofconductor branches, or else adjacent conductor branches can be presentwhich are energized both in the same direction and in differentdirections. In some embodiments, at least one pair of adjacent conductorbranches is present in the winding, in which the directions of currentflow to be applied in service are in mutual opposition. In a coilwinding of this type, the application of a tensile force to the at leastone non-conductive element according to the invention is particularlyrelevant, as the adjacent conductor branches will undergo mutualrepulsion in service, such that it is easy for the loosening of thecomposite structure of the winding to occur. This electrically-relatedloosening of the composite structure of the winding is advantageouslyprevented by the solution according to the invention, as thenon-conductive element is permanently tensioned. The tensile forceapplied, as indicated above, can be configured with sufficient strength,such that the mechanical integrity of the winding is sufficiently highto prevent any lateral displacement of the turns, even during electricaloperation.

In some embodiments, the coil winding may be employed in a fault currentlimiter. Specifically, this can comprise a superconducting fault currentlimiting device. The current limiter may comprise a resistive,inductive, or inductive-resistive current limiter. The current limitercan comprise one or more coil windings according to the invention. Inthe event of a plurality of coil windings, these can specifically bestacked in an axial direction.

In some embodiments, however, the coil winding may be employed in arotating machine, e.g. for example in the rotor or stator windings of arotor or generator. In some embodiments, the coil winding may be used asa magnetic coil for the generation of magnetic fields, specifically as asuperconducting magnetic coil for magnetic resonance imaging or magneticresonance spectroscopy.

FIG. 1 shows a schematic view of a coil winding 1 of a fault currentlimiter incorporating teachings of the present disclosure. A flat coilis represented, in which an electric conductor 3 is wound in a pluralityof turns, within a fixed winding plane, about a central winding axis A.In this case, the electric conductor comprises two conductor branches 3a and 3 b which, in the example represented, are interconnected in thecenter of the winding and are arranged in the form of a “bifilarwinding”, such that the directions of current flow Ia and Ib in theconductor branches 3 a and 3 b arranged adjacently in the winding are inmutual opposition. Between the adjacent turns of the two conductorbranches 3 a and 3 b, a non-conductive element 5 is respectivelyarranged. The total of two non-conductive elements 5 provided in thiscase thus separate the adjacent turns of the electric conductor 3 overthe entire length of the winding. Accordingly, the adjacent turns, as aresult of the insulating properties of the elements 5 are firstlyelectrically isolated and, as a result of the thickness of the elements5, are secondly maintained at a specific clearance d. The elements 5 areonly schematically represented as flat lines. In the present example,however, they also incorporate a significant extension in the radialdirection, and assume an overall three-dimensional structure, asdescribed in greater detail hereinafter.

In this case, as a result of the folding of the conductor in the centerof the coil winding, as represented, the two ends of the electricconductor 3 are both arranged in outer radial regions of the winding. Inthe first end region 9 a, the first conductor branch 3 a is connected toa first retaining element 7 a, which simultaneously functions as acontact element for said conductor branch 3 a. It can be configured, forexample, as a solid copper block. Analogously, in the second end region9 b, the second conductor branch 3 b is connected to a correspondingsecond retaining element 7 b, which likewise functions as a contactelement. In the end regions 9 a and 9 b, the two conductor branches 3 aand 3 b which are contacted at this location are respectively covered onthe outer radial side, approximately to the extent of the respectiveretaining element, by one of the non-conductive elements 5, and are thusmechanically protected to the exterior. The non-conductive elements 5are mechanically connected to the respective retaining elements 7 a and7 b. The embodiment of the coil winding 1 according to the invention,which is described in greater detail hereinafter with reference to FIG.4, differs from the prior art with respect to the exact nature of themechanical attachment of the non-conductive elements 5 to the retainingelements 7 a and 7 b.

FIG. 2 shows a detailed view of the non-conductive element 5 representedin FIG. 1. A section of the non-conductive element 5 of the coil winding1 configured as a spacer is represented, with an electric conductor 3arranged therein, in a schematic oblique view. Here, the width of thespacer is represented by B, and the direction of its longitudinalextension is represented by L.

In this case, the electric conductor 3 comprises a superconducting stripconductor, for example as a strip conductor having a high-temperaturesuperconducting layer arranged on a normally conducting substrate. Stripconductors of this type which are particularly suitable forsuperconducting current limiters are described in greater detail in DE10 2004 048 646 A1. The non-conductive element 5 is thus configured tofunction as a spacer between adjacent turns of the conductor 3. To thisend, the non-conductive element 5, in the example represented, comprisestwo parts, namely, a flat strip 18 and a corrugated strip 17. The twostrips, in the closely mutually adjacent regions—e.g. in the regions ofthe corrugation troughs represented in FIG. 2—can be mechanicallyinterconnected, for example by means of welding or adhesive bonding. Inthe region of the corrugation peaks, the corrugated strip 17incorporates recesses 21 into which, in the finished coil winding 1, thestrip material conductor 3 can be inserted, as represented in anexemplary manner in the right-hand section of FIG. 2.

By means of a non-conductive spacer of this type, as represented in anexemplary manner in FIG. 2, it can be achieved that, firstly, a specificclearance is maintained between the turns of the superconductingconductor 3, and secondly, by means of the open structure, cavities 13are constituted between the turns, through which a coolant fluid canflow. In the context of the present invention, however, theconfiguration of the non-conductive element according to FIG. 2 is to beunderstood as exemplary only. Further forms of embodiment of the spacercan be configured as described in EP 2041808 B1.

According to the prior art, coil windings of this type, as describedwith reference to FIG. 1 and FIG. 2 are secured by means of a rigidconnection of the electric conductor 3 and the non-conductive element 5to the respective retaining elements 7 a and 7 b. FIG. 3 shows aconventional configuration of the mechanical connection of this type, inthe end region 9 a, according to the prior art. FIG. 3 shows a lateralview of the end region 9 a, from an outer radial position in relation tothe retaining element 7 a shown in FIG. 1. The outer radialnon-conductive element 5 is represented which, in the left-hand sectionof the drawing, covers the underlying conductor 3.

Here, this conductor 3 is represented by a broken line only. In thiscase, the recesses 21 of the non-conductive element 5 represented arenot occupied by a conductor, as the conductor represented here issecured on the non-conductive element 5 in the corrugated strip of theunderlying layer. In the central section of the drawing, the conductor 3can be seen in full, as the corrugated strip 17 of the outernon-conductive element 5 does not extend entirely to the retainingelement 7 a and, in consequence, the conductor 3 is no longer covered atthis point.

Likewise, in the central section of the drawing, the flat strip which isarranged below the corrugated strip 17, in its central region,incorporates a recess, through which the electric conductor 3 is routedradially outwards. Accordingly, only the two outermost sections of theflat strip 18 are routed as far as the retaining element 7 a. In theconfiguration of the retaining arrangement according to the prior artrepresented, both the conductor 3 and the outermost sections of the flatstrip 18 are secured to the retaining element 7 a in a rigid connection,by means of screws 23. To this end, both the electric conductor 3 andthe sections of the flat strip 18 are inserted between two sections ofthe retaining element 7 a which are screwed together. This type offixing has the disadvantages described in the introductory section, inthat a variation in the length of the non-conductive element and/or anyloosening of the winding associated with the operation of the coilcannot be compensated. In principle, it is possible to execute a manualre-tensioning further to initial entry into service, or further to thefirst functional test. However, this is highly complex, and requires theremoval of the coil winding from the finished current limiter device.Moreover, a subsequent intervention of this type entails a risk ofdamage to the superconductor.

Finally, in a distinction from FIG. 3, FIG. 4 shows a configurationincorporating teachings of the present disclosure for the attachment ofthe winding elements to the retaining element 7 a. Here again, a lateralview of the end region 9 a is represented, from an outer radialposition. In this case, however, in a distinction from the attachmentshown in FIG. 3, the non-conductive element 5 is not routed quite as faras the retaining element 7 a. It is not directly and rigidly connectedto the latter, but is secured to the latter via elastic tensileelements. In the example represented, two such elastic tensile elements11 are present in the form of tension springs which, by means of aretaining pin 12 inserted into one of the cavities 13 between thecorrugated strip 17 and the flat strip 18, are connected to the latter.However, other means of attachment to the non-conductive element 5 arealso conceivable.

It is also sufficient that the non-conductive element 5 and theretaining element 7 a are mutually connected by a single elastic tensileelement only. It is essential that, by means of the elastic tensileelement 11, a tensile force is exerted on the non-conductive element 5,which effects the in-service re-tensioning of the non-conductive element5 and can thus offset any forces that weaken the composite structure ofthe winding. The non-conductive element 5 is thus secured to theretaining element 7 a in a manner which is dissociated from the electricconductor 3. By the continuous application of a tensile force to thenon-conductive element 5, a mechanical integrity of the coil winding canbe achieved, even in the absence of any adhesive bonding or embedding ofthe winding.

The mechanical fixing of the non-conductive element as taught herein isnot restricted to the configuration of the non-conductive elementrepresented in FIG. 2. The advantages coming therefrom are likewise notrestricted to current limiter coils having a geometry according toFIG. 1. The configurations according to FIG. 1 and FIG. 2 are to beconsidered for exemplary purposes only, in the interests of theclarification of the action of the invention. In general, the advantagesof the attachment will also apply if, for example:

-   -   the coil winding does not assume the form of a flat coil, but is        configured, for example, in the form of a solenoid coil or        saddle coil,    -   the coil winding is not bifilar, but is configured, for example,        as a winding with continuous flow of current in the same        direction in adjacent turns,    -   the coil winding is not designed for current limiting, but for        employment, for example, as a magnetic coil or a coil in an        electrical machine,    -   the end regions of the conductor do not both assume an outer        radial arrangement but, for example, one assumes an outer radial        arrangement and the other an inner radial arrangement,    -   the at least one retaining element is not simultaneously        configured as a contact element for the conductor,    -   the electrical conductor and/or the non-conductive element are        not constituted of strip materials    -   and/or if the electric conductor is not superconducting.

What is claimed is:
 1. An electric coil winding comprising: an electricconductor; a non-conductive element wound in parallel to the electricconductor throughout a number of turns forming a coil; and a firstretaining element arranged in a first end region of the coil; andwherein the non-conductive element is mechanically secured to theretaining element by means an elastic tensile element.
 2. The electriccoil winding as claimed in claim 1, wherein: the electric conductorcomprises a strip; the non-conductive element comprises a strip; and thecoil comprises a flat coil with mutually superimposed layers of theelectric conductor strip and the non-conductive element strip.
 3. Theelectric coil winding as claimed in claim 1, wherein the electricconductor comprises a superconducting conductor material.
 4. Theelectric coil winding as claimed in claim 1, wherein the first endregion is arranged in an outer radial position.
 5. The electric coilwinding as claimed in claim 1, wherein: the retaining element comprisesan electric contact element; and the electric conductor is connected inan electrically conductive manner to the electric contact element. 6.The electric coil winding as claimed in claim 1, wherein thenon-conductive element comprises a spacer disposed between individualand mutually superimposed turns of the electric conductor.
 7. Theelectric coil winding as claimed in claim 6, wherein the non-conductiveelement includes one or more cavities through which a coolant fluid canflow.
 8. The electric coil winding as claimed in claim 6, wherein thenon-conductive element comprises a corrugated strip.
 9. The electriccoil winding as claimed in claim 1, wherein the non-conductive elementcomprises a plastic material.
 10. The electric coil winding as claimedin claim 1, wherein the non-conductive element has a width greater thana width of the electric conductor.
 11. The electric coil winding asclaimed in claim 10, wherein the electric conductor is disposed at leastpartially within a recess of the non-conductive element.
 12. Theelectric coil winding as claimed in claim 1, wherein the non-conductiveelement comprises a plurality of parts.
 13. The electric coil winding asclaimed in claim 1, wherein the elastic tensile element exerts a tensileforce of at least 5 N on the non-conductive element.
 14. The electriccoil winding as claimed in claim 1, wherein: the electric conductorcomprises at least two conductor branches; and at least two adjacentconductor branches in the winding are configured for mutually opposingdirections of current flow.
 15. (canceled)